Monitoring Real-Time Signals

 

Real-time instrument signals may be monitored from either the instrument touch screen or from the controller Signal Display pane. If you choose to use the touch screen, you can access either the Status or Signal Display options. See also: Display Menu Touch Screen.

Controller Signal Display Pane

Signal Display PaneThe Signal Display pane (shown to the right) is a customizable instrument control window that allows the user to select the real time signals they want displayed during an experiment. These same signals are also available for plotting in the RealTime Plot window.

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Signal Display Pop-up Menu

Each thermal analysis instrument displays a certain set of information on the Signal Display window. Using the pop-up menu (accessed by right clicking), you can customize the signal display by selecting Customize Signal Display.  When the Customize Signal Display window appears, select or deselect the signals then click OK to close the signal selection window and display the new signals. You can reorganize the order of the signals by clicking on a signal name to display a drop-down list of signals to select from.

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DSC Instrument Signals

Listed below are all of the possible real-time DSC signals. The available signals are dependent on instrument type, mode, cell, cooler, and options installed. These signals are available for display within the Signal Display pane, as RealTime plot signals, and they are displayed on the instrument touch screen, if available. A subset of these signals are available as stored signals within the data file.

For a detailed explanation of the signals shown on the window, see the table below:

 

Signal

Description

Cell pressure, kPa

The cell pressure signal is displayed when a pressure DSC cell is installed on a DSC Q1000. The pressure within the PDSC cell is shown on the Signal Display window in kPa. This signal is stored in the data file.

Delta T

The temperature difference (in V) between the sample and the reference temperatures.

Delta Tzero

The temperature difference (in V) between the Tzero and sample temperatures.

Flange Temperature, C

The temperature of the cooling flange inside the cell.

Heat Capacity, Cp

 

 

 

 

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The deconvoluted heat capacity of a sample displayed during MDSC experiments. Heat capacity is defined as the quantity of heat required to increase the temperature of a substance by one degree (usually expressed as joules/mol/C).

The heat capacity signal is displayed when running MDSC experiments. It is the deconvoluted heat capacity of the sample. This signal is selectable and can be included in the data file.

Heat Flow, mW

 

The heat flow signal is the average or total heat flow (in mW) given off or absorbed by the sample. This signal is stored in the data file.

Heat Flow Amplitude, mW

The heat flow amplitude signal is displayed when running MDSC experiments. It is the deconvoluted peak heat flow amplitude displayed. This signal is selectable and can be included in the data file.

Heater Power, Watts

The electrical power (in watts) being sent to the heater.

Instrument clock

The time set on the current instrument. You can synchronize the instrument with the controller by using the Instrument Setup Wizard.

LNCS Liquid Detect Temperature

The temperature of the thermocouple in the liquid detect assembly. It is used to determine when liquid nitrogen is present in the exhaust gas stream.

LNCS Pressure

The pressure of the liquid nitrogen currently contained in the dewar.

Method Time, min

The time that the current method has been running.

Modulated heat flow, mW

This MDSC signal is the measured four-term heat flow signal. Its sinusoidal shape is the result of the changing sinusoidal heating rate used in MDSC. The primary value of the modulated heat flow signal is the raw, not deconvoluted heat flow signal responds to the changing heating rate transitions. This signal can be used to determine if sufficient modulation cycles occurred during a transition with the selected modulation conditions. This signal is selectable and can be included in the data file.

Modulated temperature, C

The modulated temperature signal is displayed when running MDSC experiments.  It is the measured sample temperature. This signal is selectable and can be included in the data file.

Nonreversing Heat Capacity

 

 

 

 

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The nonreversing heat capacity signal is displayed when running MDSC experiments. Nonreversing heat capacity is the portion of the total heat capacity that does not respond to temperature modulation. Transitions seen in this signal are kinetic in nature and the resulting heat flow is a function of time at an absolute temperature (evaporation, crystallization, thermoset curve, etc.). The signal is identical to the nonreversing heat flow except for the units (J/gC vs. W/g).

Nonreversing Heat Flow, mW

The nonreversing heat flow signal is displayed when running MDSC experiments. It is the total heat flow minus the reversing heat flow. This signal is selectable and can be included in the data file.

Nonreversing heat flow is defined as the kinetic component of the total heat flow. Nonreversing heat flow is calculated by subtracting the reversing signal, which is the heat capacity component, from the total heat flow. This creates a signal which contains the sum of all heat flow events except heat capacity.

Transitions seen in this signal are usually thermodynamically nonreversible at the time and temperature at which they are detected. Typical nonreversing transitions include enthalpic relaxations, cold crystallization, evaporation, thermoset cure, and decomposition.

Reference Intensity, mW/cm2

The unique design of the Q Series™ Tzero™ DSC cell allows the heat flows at the sample and reference platforms to be monitored independently. This is useful in photocalorimetry (PCA) evaluations because the light intensities at the two cell platforms can be balanced and the intensity at the sample determined directly by measuring the independent heat flows and dividing by the area of the sensors (platforms). These intensity signals are only used for PCA experiments. Therefore, they are not default-stored signals, but must be selected.

Reference Sine Angle, rad

This MDSC signal is calculated based on the heating rate, temperature modulation amplitude and period for the selected experiment. The signal is used to control the temperature modulation of the furnace. This signal is selectable and can be included in the data file, however it does not have to be stored unless the user intends to develop their own software for calculating MDSC signals.

Remaining Run Time, min

The estimated total time remaining until completion of the experiment.

Reversible Heat Flow, mW

The reversing heat flow signal is displayed when running MDSC experiments. It is the deconvoluted heat capacity multiplied by minus the program heating rate. This signal can be saved in the data file.

Reversing heat flow is defined as the heat capacity component of the total heat flow. Reversing heat flow is calculated by multiplying the heat capacity signal by the average heating rate. It is multiplied by the average heating rate (constant) in order to scale the heat capacity signal to the same size (in mW) as the total heat flow signal, which is the average heat flow signal at the average heating rate.

Transitions seen in this signal are usually thermodynamically reversible at the time and temperature at which they are detected. Typical transitions include the glass transition and most crystalline melts.

Reversing Heat Capacity

 

 

 

 

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The reversing heat capacity signal is displayed when running MDSC experiments. Reversing heat capacity is the portion of the total heat capacity that responds to temperature modulation. It is identical to the reversing heat flow signal except that it is expressed in heat capacity (J/gC) instead of heat flow (W/g) units. It typically includes all transitions where there is a change in heat capacity such as the glass transition, plus that portion of the melting process which has a relatively short time constant and can, therefore, follow the temperature modulation.

Sample Intensity, mW/cm2

The unique design of the Q Series™ Tzero™ DSC cell allows the heat flows at the sample and reference platforms to be monitored independently. This is useful in photocalorimetry (PCA) evaluations because the light intensities at the two cell platforms can be balanced and the intensity at the sample determined directly by measuring the independent heat flows and dividing by the area of the sensors (platforms). These intensity signals are only used for PCA experiments. Therefore, they are not default-stored signals, but must be selected.

Sample Purge Flow, mL/min

The flow rate of the gas being supplied to the cell.

Segment Time, min

The total time the current segment has been running.

Set Point Temperature, C

The set point temperature is the temperature that the furnace is being instructed to reach.

Temperature, C

The current temperature of the sample.

Temperature Amplitude, C

The temperature amplitude signal is displayed when running MDSC or MTGA experiments. It is the deconvoluted peak temperature amplitude. This signal is selectable and can be included in the data file.

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